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Cisterns making a comeback

Water storage has a long history in Keys

By Dick Conklin
Keys Sunday contributor

The Keys have always had cisterns.

The environmental movement has attracted new interest to the ancient technology, which uses storage tanks to store collected rainfall. They can be underground (such as converted septic tanks), at ground level, or on elevated stands that use gravity feed instead of a pump to deliver the water, even when the power is off. When their water is not pure enough for drinking, they can be used for irrigation purposes. Cisterns sanitary enough to store potable water can be used to offset the need for utility-supplied drinking water.

Another benefit of cisterns is that they can divert water from buildings, streets and parking lots that would otherwise become stormwater runoff — greasy, dirty water that ends up in the ocean or bay, damaging the living reef that surrounds the Keys.

But can you drink it?

Hammerstrom says yes. “Because most, if not all utility water is pumped from the ground, they have a disadvantage compared to rainwater harvesters because water — the universal solvent — picks up any contaminants that are present. When the water one uses is pumped from the ground, all of the chemical contaminants of our modern society are potentially present and can be pumped along with the ground water.

“Utilities spend lots of money to clean up the water, and the Florida Keys Aqueduct Authority is one of the best. The U.S. Environmental Protection Agency has a long list of contaminants that are allowed in small quantities, however. In the news lately is the fact that the EPA does not require testing for, nor do they have standards for a broad category of chemicals known as Personal Care Products and Pharmaceuticals.

“Rainwater, however, suffers from fewer contaminants. Rain is fundamentally distilled water. It evaporates from surface sources, becomes a cloud and then precipitates the condensed water back to earth. There are airborne contaminants, but in the Keys, and in South Florida in general, we have far fewer airborne contaminants than folks downwind of a coal-fired power plant, for example.

“Removing those potential airborne contaminants from rainwater is much less difficult than removing the much longer list of contaminants from ground water.

“As a result, we use the filtered rainwater for our primary drinking and cooking water source. It is very pure and tastes great.”

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